The mortality rate of U.S. chronic hemodialysis patients is higher than that in other industrialized nations. Available data suggest that this high mortality rate is partially a result of inadequate delivery of dialysis. The MMHD is a prospective, randomized, multicenter, two-by-two factorial trial sponsored by NIDDK to determine if increasing the amount of delivered dialysis (as assessed by a two-pool, variable-volume urea kinetic model) and using high flux biocompatible dialysis membranes would improve the clinical outcome of these patients. This application describes the University of Utah Dialysis Program (together with the Salt Lake City VA Medical Center dialysis unit) and proposes that this Program participates as a Clinical Center in the MMHD Full Scale Study. The University of Utah Dialysis Program consists of 7 dialysis units, some of which are located in suburban communities, that have common administrative and medical guidelines originating from the University headquarters. The VA-unit is also closely affiliated and has similar protocols. The investigators in this proposal have significant expertise in their respective areas. Both the institution and the investigators have a long tradition in laboratory and clinical dialysis research. They have recently performed several clinical studies involving patients from the different dialysis units within the Program. The P.I. has also participated in several multicenter clinical trials with centers outside Utah. The ESRD population in this Program has been growing. The number of in-center hemodialysis patients, as of December 31, 1993, was 237, of which 37% were diabetic. The majority of these patients are Caucasian (78%), but there is a significant fraction (5%) of Native Americans. This Program will recruit approximately 108 patients during the first 18 months of the Study and randomly allocate 60 of them to 4 hemodialysis treatment strategies that differ in the amount of delivered dialysis and/or the type of dialysis membrane. Sixty patients will be maintained throughout the study by using a "recruit to replace" strategy. Many of the medical and technical aspects of therapy, including nutritional intake, will be standardized during the baseline and a 60 month follow-up period. The primary outcome is death of the patient; secondary outcomes include non-access related hospitalization, hospitalization for heart disease or infection, and declining serum album in. The results from this trial will guide hemodialysis therapy in the future.